Environmental controls on calcareous nannoplankton response to the Cretaceous/Paleogene mass extinction in the Tethys realm

Abstract

The Cretaceous/Paleogene (K/Pg) mass extinction exhibits a remarkable geographical contrast between the Northern and Southern Hemispheres in extinction severity and recovery response, yet environmental facets of this extinction selectivity are still poorly known. Here, we statistically analyze the calcareous nannofossil counts from six K/Pg boundary sections from the Tethys Ocean, representing a northern subtropical depth transect from continental shelf to abyssal plain. Our analyses reveal that calcareous nannoplankton from all environments underwent an ecological crisis and responded similarly to the K/Pg environmental catastrophe, providing a solid basis for paleoecological reconstruction with nannofossils across the world oceans. Most interesting is the environment-dependent response pattern, as demonstrated by the increasing separation between shelf and deep ocean sites that signals a deepened environmental stress gradient. This environment-dependent response can be attributed to the marked difference in primary production and community composition between shelf and pelagic ecosystems, as well as the smaller accommodation and buffering capacity of shelves, while the progressive removal of susceptible species with increasing water depth seems to be of little influence.